I have a few apps and one told me I ovulated on the 13th another said I ovulated on the 17th I had unprotected sex on the 13.

Another one told me that I ovulated last Saturday so the 24th I had sex on that day.

I have never been pregnant and I'm am 20 I have gone to the doctor's and they done an ultrasound for me and said nothing was wrong with my ovaries and stuff I then had blood tests done for thyroid problems and all of that and the only thing that they said was wrong is my folic acid was down but I still feel something is wrong I just don't know what I have an irregular period some times I can miss a month my longest cycle this year was 54 days but other then that it's Ben anywhere between 26 to 34 days I don't know what to do.